title: Impairment of exploratory eye movement in schizophrenia patients and their siblings.
abstract: OBJECTIVE
  Previous family, adoption and twin studies of schizophrenia have shown that genetic factors contribute significantly to the risk of schizophrenia. The aim of the present study was therefore to investigate whether exploratory eye movement (EEM) abnormalities are related to the genetic markers linked to schizophrenia.
  
  
  METHODS
  Twenty-three probands with schizophrenia, 23 of their healthy siblings (23 proband-sibling pairs), and 43 unrelated normal controls performed EEM tasks. Two parameters were measured: (i) number of eye fixations in responsive search (NEFRS) and (ii) responsive search score (RSS).
  
  
  RESULTS
  Abnormalities in NEFRS and RSS were more frequent in schizophrenia probands than in their unaffected siblings and in normal controls, and were also more frequent in the healthy siblings than in normal controls. Thus, the EEM test performances of the healthy siblings were intermediate between those of the probands with schizophrenia and those of normal controls.
  
  
  CONCLUSIONS
  Abnormalities of the EEM test parameters may be related to the genetic etiology of schizophrenia. The use of EEM parameters as an endophenotype for schizophrenia may facilitate linkage and association studies in schizophrenia.
authors.affiliation: Department of Neuropsychiatry, Nihon University, School of Medicine, Tokyo, Japan. sakae@med.nihon-u.ac.jp
authors.forename: Sakae
authors.initials: S
authors.lastname: Takahashi
authors.forename: Eiichi
authors.initials: E
authors.lastname: Tanabe
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yara
authors.forename: Masato
authors.initials: M
authors.lastname: Matsuura
authors.forename: Eisuke
authors.initials: E
authors.lastname: Matsushima
authors.forename: Takuya
authors.initials: T
authors.lastname: Kojima
mesh_terms: D000328:Adult; D001288:Attention; D005106:Exploratory Behavior; D053483:Eye Movement Measurements; D005133:Eye Movements / Q000235:genetics*; D005260:Female; D005403:Fixation, Ocular; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D010641:Phenotype; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics*; D012565:Schizophrenic Psychology; D012569:Schizotypal Personality Disorder / Q000175:diagnosis / Q000235:genetics; D055815:Young Adult